Today 
Hungry, voracious caterpillars can be found in a wide variety of colours and sizes. Some feed on fruits, roots and stems, but the likes of the cabbage white butterfly, hawk moth and winter moth feed on leaves. Although they may at first seem an attractive form of wildlife, large colonies can strip leaves bare.
Solution
Organic
Pick them off by hand and dispose of them, keeping a special lookout after dark. In the greenhouse or conservatory, you could use the biological control Trichogramma brassicae, which is a tiny wasp that targets caterpillar eggs.
Chemical
The moment you find signs of caterpillars, spray the plants with pyrethrum or bifenthrin.
